1. Field of the Invention
The present disclosure relates to a heat conductor and a device including the heat conductor, and particularly to a heat conductor in a rubber composition for shielding electromagnetic waves and to a device including the heat conductor.
2. Description of the Related Art
In recent years, electronic devices have been miniaturized and achieved greater functionality in many fields of, for example, households, offices, industries, and health care. The electromagnetic waves radiated from, for example, enclosures of electronic devices sometimes enter other electronic devices and cause the other electronic devices to malfunction.
As such, electronic devices malfunction due to electromagnetic waves from the outside. Thus, to prevent such malfunction, for example, the electronic devices are covered with electromagnetic wave shielding materials so that electromagnetic waves do not enter the electronic devices.
Conventional examples of the electromagnetic wave shielding materials include metal plates such as aluminum plates, metal-fiber wire meshes made of, for example, stainless-steel, plating films, and materials each having a surface treated to be conductive. These materials are separately used according to the application or the cost. Furthermore, the examples of the electromagnetic wave shielding materials also include a rubber material containing carbon for conductivity. This rubber material produces advantages of low cost, durability, and adding sealability to a part to which the rubber material is attached (Japanese Patent No. 4759852).
Since the electromagnetic wave shielding materials including this rubber material are used in a compressed state for a long period of time, they require not only sufficient conductivity but also excellent compression restorability as mechanical properties, that is, a low compression set. However, an electromagnetic wave shielding material containing a smaller amount of a filler for maintaining the rubber properties exhibits insufficient electromagnetic shielding effect. Thus, the electromagnetic wave shielding materials including this rubber material require the compatibility between the rubber properties and the electromagnetic shielding effect.
For example, JP 4759852 suggests that a rubber material containing a plasticizer, graphite fillers, and a reinforcing agent satisfies the compatibility between the rubber properties and the electromagnetic shielding effect.
The electromagnetic wave shielding materials including the rubber materials containing fillers linearly improve the electromagnetic shielding effect almost in proportion to the amount of the fillers. In other words, as the amount of the fillers increases, the electromagnetic shielding effect of the electromagnetic wave shielding materials is increased.
However, the increased amount of the fillers reduces the moldability of the electromagnetic wave shielding materials. As a result, the electromagnetic wave shielding materials are hardened, and the rubber elasticity decreases.
As described in JP 4759852, a composition in which graphite fillers are dispersed into a matrix of a thermoplastic resin has limitations in improvement in the electromagnetic shielding effect.